Different types of variable frequency, variable voltage power supplies are known, but they all have singular inherent disadvantages, particularly in cost and in size. For example, the response to transients by variable voltage link inverters with phase controlled rectifiers and choppers is unsuitable for some applications and also such inverters require an expensive DC filter. Pulse width modulated (PWM) inverters of the SCR type have difficulty in maintaining acceptably low motor current ripple and necessitate reactive enegy storage and expensive commutation circuits. The SCR's of known PWM inverters must be of the high-speed, and thus expensive, type because they switch at carrier frequency. Further, known inverters of the SCR type having a voltage-controlling transistor chopper commutate the SCR's off while they are conducting load current and thus require large and expensive inductive and capacitive elements in the commutation circuits. The transistor switches coupled to the high voltage bus of PWM transistor inverters are very expensive because they require high power, continuous, isolated drive signals which make the interface circuits thereto costly.